Anodal/cathodal
tDCS have facilitatory/inhibitory effects, respectively, on the stimulated
cortical networks. Here we used concurrent tDCS-fMRI to test whether
anodal/cathodal tDCS result in BOLD-fMRI signal changes during a resting
condition. Furthermore, we examined tDCS-effects on brain activation during
voluntary finger tapping. Anodal/cathodal tDCS over left M1 induced no
detectable BOLD signal change. However, anodal/cathodal tDCS combined with
finger tapping resulted in a decreased BOLD response in SMA, but not M1, in
comparison to voluntary finger tapping without stimulation. This suggests
that in contrast to the rest condition the combination of neuronal
polarization and motor activation induces inhibition in remote brain areas.